A composite key is a primary key that consists of two or more attributes that uniquely identify a record.

Explanation:

• Used when a single column is insufficient for uniqueness.
• Common in junction tables that handle many-to-many relationships.

Example SQL Composite Key:

sqlCopyEditCREATE TABLE Enrollment (
    student_id INT,
    course_id INT,
    enrollment_date DATE,
    PRIMARY KEY (student_id, course_id)
);

Here, student_id and course_id together form a composite key.